This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my application INK CARTRIDGE WITH SEPARATE MAGNETS filed with the Korean Industrial Property Office on Aug. 13, 2001 and there duly assigned Ser. No. 48737/2001.
1. Field of the Invention
The present invention relates to an ink cartridge with separate magnets, and more particularly, to an ink cartridge for detecting a state of ink consumption using two separate upper and lower magnets in an ink chamber by detecting a magnetic flux having a predetermined level when the two magnets are combined.
2. Description of the Related Art
Ink cartridges used for ink jet printers contain ink and eject ink droplets through a head, so that an image of a predetermined color can be printed on a printing medium. FIG. 1 is a sectional view of an ink cartridge with two chambers, which is disclosed in U.S. Pat. No. 6,012,808. Referring to FIG. 1, an ink cartridge 1 includes two chambers, i.e., an ink containing chamber 10 and a sponge chamber 20, separated by an internal vertical partition 30. The sponge chamber 20 is filled with a sponge 24, and the ink containing chamber 10 supplies ink to the sponge chamber 20 through a clearance 32 formed in a lower portion of the vertical partition 30. An ink supply outlet 22 through which ink is supplied to an ink jet printer head (not shown) is formed at one side of the sponge chamber 20. An air vent 26 is formed at the top of the sponge chamber 20. A light reflecting plate 12 is provided at a lower portion of the vertical partition 30 in the ink containing chamber 10. A light emitting element 13 for radiating light onto the light reflecting plate 12 and a light receiving element 14 for detecting light reflected from the light reflecting plate 12 are provided outside the ink containing chamber 10 to face the light reflecting plate 12.
In the ink cartridge 1, when ink in the sponge 24 is exhausted, ink is absorbed into the sponge 24 by the capillary attraction of the sponge 24 and is thus supplied to the sponge chamber 20. Here, the air flowing into the sponge chamber 20 through the air vent 26 helps ink in the ink containing chamber 10 to be supplied to the sponge chamber 20. When the ink level in the ink containing chamber 10 is below the light reflecting plate 12 as ink is consumed, light emitted from the light emitting element 13 is reflected from the light reflecting plate 12. When the reflected light is detected by the light receiving element 14, it is recognized that there is almost no ink left in the ink cartridge 1.
However, when the ink cartridge 1 having the above structure is installed in the printer head, bubbles may be introduced into the head, thereby degrading printing quality. Accordingly, suction is applied to remove bubbles, which wastes ink. In addition, use of an optical sensor such as the light emitting element 13 or the light receiving element 14 may result in erroneous sensing due to, for example, scattered reflection in residual ink. Moreover, a cartridge container 2 is required to have good light transmissivity so that light can be transmitted through the cartridge container 2.
It is therefore an object of the present invention to provide an improved ink cartridge having an improved apparatus for detecting when the ink cartridge runs out of ink.
It is another object of the present invention to embody the magnets and the magnet sensor in each chamber of a multicolored printhead where the magnets in one chamber do not influence the magnets in an adjacent chamber.
These and other objects of this invention can be achieved by a structure where there is provided an ink cartridge including an ink container, which includes first and second chambers II partially separated by a vertical partition formed therewithin for containing ink, and a head for ejecting the ink from the first chamber filled with an ink-soaked sponge onto a printing medium in the form of droplets. Near the head, the first chamber includes a filter located at a bottom portion of the sponge, and an ink supply pipe for supplying the ink which has passed through the filter to the head. The second chamber includes a magnet float floating on the surface of the ink in the second chamber and having a first magnet embedded inside, and a second magnet provided in the bottom surface of the second chamber. The ink cartridge includes a flexible printed circuit board disposed around the head of the ink container to control the head, The ink cartridge also includes a magnet sensor near the second magnet and outside the ink container for detecting magnetic flux caused by the first magnet contacting the second magnet triggering a signal to a user when the magnetic flux experienced by the sensor reaches or exceeds a predetermined threshold level. Preferably, the magnet float is made of a foam-molded polypropylene resin, and the first magnet is a plastic magnet. Also, preferably, the magnet sensor is a Hall effect sensor which outputs a detection signal when a magnetic flux of at least a predetermined level is detected.